Three-dimensional balun

Abstract

A three-dimensional balun is disclosed by laminating alternate layers of conductor and dielectric substrate on top of each other to create a microwave circuit. The laminated layers are constructed in a transmission line configuration, corresponding to an equivalent circuit, wherein the first and third transmission lines, the fifth and seventh transmission lines, the second and fourth transmission lines, and the sixth and eighth transmission lines are pairs of coupling lines; one end of the sixth transmission line is defined as an input; one end of the seventh transmission line is defined as a first output; one end of the eighth transmission line is defined as a second output. When signals close to the center frequency of the operating balun are input from the unbalanced side, the signals are converted and then output through the first and second outputs having the same amplitude and producing 180-degree phase shifts.

1. A three-dimensional balun, comprising:
 multiple conductor layers made of metal material and having a dielectric substrate layer interposed between every two conductor layers, where each conductor layer includes a circuit topology, and the dielectric substrate layers are planar plates, wherein 
 the conductor layers are in transmission line configuration, in such a way that 
 the first conductor layer includes first and second transmission lines, a first terminal, and a second terminal; 
 the second conductor layer includes third and fourth transmission lines; 
 the third conductor layer includes a ground electrode and a fifth terminal; 
 the fourth conductor layer includes fifth and sixth transmission lines, and a third terminal; and 
 the fifth conductor layer includes seventh and eighth transmission lines, and a fourth terminal; and 
 the sixth conductor layer is a ground electrode; 
 the three-dimensional balun characterized in that 
 one end of the first transmission line is connected to one end of the fifth transmission line through a via core, passing through multiple interlayer dielectric substrates in between, while another end of the first transmission line is connected to the fourth terminal through a via core, passing through interlayer dielectric substrates in between, where these two via cores are not connected to the third and sixth conductor layers; 
 one end of the third transmission line is connected to one end of the fifth terminal through a via core, passing through multiple interlayer dielectric substrates in between, while another end of the third transmission line is connected to one end of the seventh transmission line through a via core, passing through interlayer dielectric substrates in between, where these two via cores joining two ends of the seventh transmission line are not connected to the third and sixth conductor layers; 
 one end of the second transmission line is connected to one end of the sixth transmission line through a via core, passing through interlayer dielectric substrates in between, while another end of the second transmission line is connected to the fourth terminal through a via core, passing through interlayer dielectric substrates in between, where these two via cores are not connected to the third and sixth conductor layers; 
 one end of the fourth transmission line is connected to the fifth terminal through a via core, passing through interlayer dielectric substrates in between, while another end of the fourth transmission line is connected to one end of the eighth transmission line through a via core, passing through interlayer dielectric substrates in between, where these two via cores disposed on two ends of the eighth transmission line are not connected to the third and sixth conductor layers; 
 the first and third transmission lines, the fifth and seventh transmission lines, the second and fourth transmission lines, and the sixth and eight transmission lines form pairs of coupling lines respectively; and 
 one end of the sixth transmission line being defined as the third terminal is to be an input port, passing through interlayer dielectric substrates, where the input port and the via core are not connected to the third and sixth conductor layers. 
 
   
   
     2. The three-dimensional balun as claimed in  claim 1 , wherein the balun is composed of multiple conductor layers and dielectric substrate layers corresponding to an equivalent circuit, comprising:
 a first transmission line, a second transmission line, a third transmission line, a fourth transmission line, a fifth transmission line, a sixth transmission line, a seventh transmission line and an eighth transmission line, wherein 
 the third and fourth transmission lines are grounded; the fifth, first, second and sixth transmission lines are connected in series; the seventh and third transmission lines are connected in series; the fourth and eighth transmission lines are connected in series, in such a way that the first and third transmission lines, the fifth and seventh transmission lines, the second and fourth transmission lines, and the sixth and eighth transmission lines are pairs of coupling lines respectively. 
 
   
   
     3. The three-dimensional balun as claimed in  claim 2 , wherein when signals close to the center frequency of the operating balun are input from the unbalanced side, the signals are converted and then output through the first and second terminals having same amplitude and producing 180-degree phase shifts. 
   
   
     4. The three-dimensional balun as claimed in  claim 2 , wherein the balun is constructed with each of the transmission lines set to be about 1/(2*n) of a wavelength long at the center frequency, where n is the number of layers excluding ground planes. 
   
   
     5. The three-dimensional balun as claimed in  claim 2 , wherein the balun extends to n layers configuration, and the total transmission line length is about a wavelength long at the center frequency. 
   
   
     6. The three-dimensional balun as claimed in  claim 2 , wherein the dielectric substrate layers are formed from low-temperature co-fired ceramic (LTCC) and/or FR4 substrates. 
   
   
     7. A three-dimensional balun, comprising:
 multiple conductor layers being made of metal materials and having a dielectric substrate layer interposed between every two conductor layers, where each conductor layer includes a circuit topology, and the dielectric substrate layers are planar plates, where the conductor layers are electrically connected through interconnecting vias to form pairs of matched coupler lines respectively, and alternate layers of conductor and dielectric substrate are constructed to form a vertical circuit corresponding to an equivalent circuit, comprising: 
 a first transmission line, a second transmission line, a third transmission line, a fourth transmission line, a fifth transmission line, a sixth transmission line, a seventh transmission line, and an eighth transmission line, wherein the third and fourth transmission lines are grounded; the fifth, first, second, and sixth transmission lines are connected in that order; the seventh and third transmission lines are connected; and the fourth and eighth transmission lines are connected, wherein 
 the first and third transmission lines, the fifth and seventh transmission lines, the second and fourth transmission lines, and the sixth and eighth transmission lines are pairs of matched coupler lines respectively. 
 
   
   
     8. The three-dimensional balun as claimed in  claim 7 , wherein when signals close to the center frequency of the operating balun are input from the unbalanced side, the signals are converted and then output through the first and second terminals having same amplitude and producing 180-degree phase shifts. 
   
   
     9. The three-dimensional balun as claimed in  claim 7 , wherein the balun is constructed with each of the transmission lines set to be 1/(2*n) of a wavelength long at the center frequency to meet the impedance transformation requirements for coupled lines, where n is the number of layers excluding ground planes. 
   
   
     10. The three-dimensional balun as claimed in  claim 7 , wherein the dielectric substrate layers of the balun are formed from low-temperature co-fired ceramic (LTCC) and FR4 substrates.